Question about the pamameters of Arcto in sverchok's "Profile Parametric Node"
This node was intended to closely resemble the SVG style of specifying paths, and you should really look at what SVG specs say about ArcTo 

;; straight from the svg specs
(rx ry x-axis-rotation large-arc-flag sweep-flag x y)


For a deeper description see this github issue tracker post:
https://github.com/nortikin/sverchok/issues/350#issuecomment-51353886